1. Field of the Invention
The present invention relates to a method of fabricating an end face light emitting type LED (light-emitting diode), one type of LED's to be used, for example, in an electrophotographic printer as a light source and in others, and further relates to a light-emitting diode array device including an array of the end face light emitting type LED's.
2. Description of the Prior Art
LED's have been widely used in the form of LED arrays each including a plurality of the LED's. One type of these LED arrays is called an end face light emitting type LED array. Structures and fabricating methods of the end face light emitting type LED arrays are disclosed, for example, in Japanese First (unexamined) Patent Publications Nos. 2-125765 and 5-31955.
The former publication discloses a method, wherein a semiconductor wafer in the laminated form of an n-side electrode, an n-type GaAs buffer layer, an n-type AlGaAs layer, a p-type AlGaAs region and a p-side electrode is diced into a plurality of end face light emitting type LED arrays. In the end face light emitting type LED array of this type, by applying the forward voltage across an pn junction between the p-type AlGaAs region and the n-type AlGaAs layer to allow the current to flow therethrough, the electric energy can be directly converted into light.
The latter publication discloses a method, wherein light-emission end faces are formed on a semiconductor wafer having a double hetero structure by means of the dry etching using chlorine gas.
However, in the conventional end face light emitting type LED array fabricating methods, there have been the following problems:
In each of the former and latter fabricating methods, when forming the light-emission end faces after the formation of the p-type regions working as light-emission layers, the light-emission end faces are formed in a manner which has no close relationship with the formation of the p-type regions. Specifically, the light-emission end faces are formed by dicing the semiconductor wafer into the LED arrays using a dicing machine with a high-speed rotating diamond blade, or the light-emission end faces are formed on a side of a concave portion which is formed by etching end portions of the LED's using the photolithography and dry etching techniques.
In these conventional fabricating methods, a positional misalignment of the light-emission end faces may occur due to insufficient alignment accuracy during the dicing process and insufficient accuracy of the dicing device or due to misalignment of masks in the photolithography. If such a positional misalignment of the light-emission end faces occurs, sizes of the p-type regions in a plan view of the semiconductor wafer are subjected to change. Thus, for achieving uniform emitted-light quantities, it is necessary to feed the current in proportion to sizes of the p-type regions. Accordingly, particularly in case of a constant-current driven type LED, since the supplied current is constant, unevenness in emitted-light quantity is caused.